Bottom Line:
Varietal differences in defence responses provide insights into the mechanisms of resistance and are a key resource for plant breeders.Transient overexpression of TcNPR1, a major transcriptional regulator of the SA-dependent plant immune system, also increased pathogen tolerance in cacao leaves.These experiments revealed critical insights regarding the molecular differences between cacao varieties, which will allow a better understanding of defence mechanisms to help guide breeding programmes.

Figure 2: Functional analysis of TcNPR1. (A) Representative images of lesions from control and TcNPR1 transiently transformed leaves 2 d after Phytophthora tropicalis inoculation. (B) qRT-PCR analysis of TcNPR1 transcript 2 d after vacuum infiltration. Ctrl, control; NPR1, TcNPR1overexpression. Bars represent means ±SE of three biological replicates. (C) Average lesion areas from control and TcNPR1 overexpressing leaves were measured 3 d after inoculation using ImageJ. Bars represent the means ±SE of measurements from 12 lesion spots from four leaf discs of each genotype. The asterisk denotes a significant difference determined by single factor ANOVA (P<0.05). (D) Pathogen biomass was measured at the lesion sites by qPCR to determine the ratio of pathogen DNA to cacao DNA 2 d after inoculation. Bars represent four biological replicates, each with three technical replicates. The asterisk denotes a significant difference determined by single factor ANOVA analysis (P<0.05).

Bottom Line:
Varietal differences in defence responses provide insights into the mechanisms of resistance and are a key resource for plant breeders.Transient overexpression of TcNPR1, a major transcriptional regulator of the SA-dependent plant immune system, also increased pathogen tolerance in cacao leaves.These experiments revealed critical insights regarding the molecular differences between cacao varieties, which will allow a better understanding of defence mechanisms to help guide breeding programmes.